High-potential insulator.



E. M. HEWLETT. HIGH POTENTIAL INSULATOB. AAAAAAAAAAAAAAAAAAAAAAAA 8.

1,077,711. Patented Nov. 4, 1913.

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MBIAPLANOGRAPH C0 WAsmNm-ON D c E. M. HEWLETT. HIGH POTENTIAL INSULATOR.

APPLIUAToN FILED MAY 5, 1908.

1,077,71 1 Patented Nov. 4, 1913.

,Il .SHEETS-SHEBT 2. ll l YWZUeSSeS: //7 V617 zio/x EDWARD M- HEWLETT, or SCHENEGTADY, New reali., casistica To Gamarra ELECTRIC COMPANY, e conrosarron or new YORK.

mcafee-Tamm; .INSULArQa To @ZZ 'whom t may concert/t Be it known that I, EDWARD M. HEWLETT, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in High-Potential Insulators, of which the following is a speciiication.

The present invention relates to insulators for elect-ric conductors, and more particularly to insulators of the post type for conductors carrying currents of exceedingly high potential.

rlhe ordinary form of insulator post is designed to be mounted on a wood or iron pin which extends through a central bore to near the top of the insulator to which the electric conductor is attached. The iron pins are good conductors at all times and the wood pins are good conductors when wet and fair conductors when dry, especially when the circuit conductor is under high potential, so that the electric st-resses acting to break down or puncture the insulating wall between the pin and the circuit conductor are localized at the weakest section of the insulater, in the vicinity of the end of the supporting pin.

The object of my invention is to provide an insulator of the post type which may be mounted without a supporting pin and in which the electric stresses will be widely distributed and the tendency to rupture reduced to a minimum.

In carrying` out the invention, I provide a long insulator' post consisting of a plurality of transverse sections securely connected end to end, and connect the post to its support by a clamp which engages the larger end thereof, while the circuit conductor is secured by means engaging the opposite end ot the post, thereby leaving practically the full length of the post in a condition to operate as a barrier to the passage of current from the electrified parts carried thereby to the support on which the post is mounted.

For a more complete understanding of the invention, reference may be made to the accompanying drawings forming a part of this specification, in which- Figure 1 shows two posts, one in side elevation and one in longitudinal section with a circuit breaker or switch mounted on Specification of Letters Patent.

Application @led May 5, 1908.

Patented Nov. 4,1913.

Serial No. 430,98?.

the outer ends thereof; Fig. 2 is an end elevation; and Fig. 3 is an enlarged side elevation of the outer ends of the posts and the parts carried thereby.

The insulator post, as shown in Fig. 1, consists ot' three sections 1, 2 and 3 of ceramic or other suitable insulating material made frusto-conical in shape and hollow. It is to be understood that the number of sections may vary according to the potential ot the circuit carried by the posts. The larger base section 1 is formed with a peripheral flange 4 at its larger end with which a clamp 5 is adapted to engage. The clamp consists Of segmental plates having i'ianges through which the wall bolts 6 are adapted to pass. The smaller end of section l has a rabbeted recess T for receiving a complementary projection 8 of section 2 and a securing medium 9. of glaze, cement, etc. 'Ihe upper end ot section 2 is formed substantially like the smaller end of section 1 for the reception of a complementary projection on outer section 3. Section 3 is closed at its smaller end and provided with a peripheral groove 10 for the reception of the clamping` means by which the electrified parts are secured to the post. The exterior surface of the post is ribbed or iiuted in order to increase the creepage surface. The inner surfaces of the several sections have a series ot grooves 11 formed therein in order to provide a greater creepage surface for the electric current in case the material ot which the insulator is formed should become cracked or ruptured.

The metallic caps 12 carried by the smaller ends of the post are formed with two main side arms 13 which extend on opposite sides of the insulator into line with the groove 10 and transversely apertnred for the reception ot screw-threaded ends ot a U-shaped clamping band 14. A segmental connection 15 extends trom one arm 13 to the opposite arm and is adapted to lie in the groove 10, and a third arm 16 connects the middle point of the connector with the main portion of the cap. A packingmember 17 of flexible fiber is interposed between the clamping members 14 and 15 and the bottom ot the groove 10. Each of the arms 13 and 16 has a diagonally tapped hole for the reception of a set screw 18 which impinges at its inner end against a ring or plate 19 resting against the end of the post whereby the cap 12 may be accurately positioned or leveled with relation to the post and also a certain tension imposed upon the clamping means. The caps 12 carry on their outer surfaces contact clips which are secured thereto by screws 21, andin the construction shown the upper contact clip 20 is adapted to receive the free end of a switch blade 22 and has a latch 23 pivoted thereon and tensioned by a spring 24. The lower contact clip 20 is made double to receive the bifurcated end of the switch blade 22. The switch blade is preferably provided with an S-shaped hook 25 whereby the switch may be opened or closed by a pole hook (not shown) and also with a stop projection 26 near the hinged end which is adapted to engage the lower contact clip 2O when the blade is in open position as indicated in dotted lines in Fig. 3. Terminals 27 for the circuit conductors are connected to the respective Contact clips by means of nuts 28.

I do not desire to restrict myself to the particular form or arrangement of parts herein shown and described, since it is apparent that they may be changed or modified without departing from my invention.

VVihat I claim as new and desire to secure by Letters Patent of the United States, is,'

1. The combination with an insulator post, of a metallic cap having means for coupling to the end of said post, and means for angularly adjusting or leveling said cap thereon.

2. The combination with an insulator post having a grooved end, ofra metallic cap having a clamp for engaging the said grooved end, an adjustable means carried by said cap for angularly adjusting or leveling it with relation to the said post.

3. rlhe combination withv an insulator post, of a metallic cap having means for coupling to the end of said post, a plate on the end of said post, and means carried by the cap for engaging said plate and operating to adjust or level said cap with relation to said post.

In witness whereof, l have hereunto set my hand this 2nd day of May, 1908.

EDTWARD M. HEWLETT.

litnesses BENJAMIN B. HULL, HELEN ORFORD.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents, i Washington, D. C. 

